APPENDIX D. Ixvii 



periods of drought. This consists in the formation of the 

 so-called ' peculiar fruit ' of the ProtonemecE, which may be 

 produced on any part of the plant, under the form of a 

 brownish ovoid mass made up of four or more cells. These 

 are supposed to be ' resting gemmae/ the production of 

 which is probably ' one of the means by which the life of 

 the plant is preserved during severe trials of drought and 

 cold.' Each one of them seems to be a sort of compound 

 gonidium, and from any one or more of its constituent cells 

 confervoid filaments may ultimately sprout. 



3. 'But this is not the only method by which the con- 

 fervoid filaments are reproduced: any one of the cells de- 

 tached from the other is capable of continuing the growth 

 of the filament in the same manner as each is capable of 

 doing whilst forming part of the filament, by branching and 

 division, as I have before noticed. And there is a great 

 tendency for these cells to separate from each other, more 

 particularly in the older filaments ; but whether old or young 

 they may bulge out on any side, and form a branch which, 

 segmenting, becomes a true filament.' The separated cells 

 may be somewhat elongated, though more frequently they 

 are spherical, having dropped off from the ends of the fila- 

 ments where three or four others have assumed nearly the 

 same form \ The green contents of these separated globular 

 cells, or gonidia, may be granular or homogeneous, and 

 they may or may not contain a central nucleus, as is ob- 

 served in the gonidia of Lichens. Others become more or 

 less altered in form and appearance, -and exactly resemble 

 some of the supposed independent forms of Confervae de- 

 scribed by the older algologists e. g. C. multicapsularis and 

 C. umbrosa. Under the influence of warmth and moisture 

 these globular or elongated cells (a) give rise to filaments ; 



1 These cells also assume a deeper and brighter green colour. 

 e 2 



